Improve TcCanonical.unifyWanted and unifyDerived
authorSimon Peyton Jones <simonpj@microsoft.com>
Fri, 14 Oct 2016 16:35:38 +0000 (17:35 +0100)
committerSimon Peyton Jones <simonpj@microsoft.com>
Fri, 21 Oct 2016 16:16:07 +0000 (17:16 +0100)
commit6ddba64287fe07df3b2df1f3db974b03945fc07f
tree7fb1647acc0fcf649c77118607906511947ba1fc
parente1fc5a3351bc02dc059db5c2a1079b04db18b401
Improve TcCanonical.unifyWanted and unifyDerived

When debugging something else I noticed that these functions
were emitting constraints like
   [W] a ~ a
which is plain stupid.  So I fixed it not to do that.  Should
result in fewer constraints getting generated.
compiler/typecheck/TcCanonical.hs